U.S.-backed Syrian forces are closing in on Islamic State (IS) militants inside the town of Manbij in Syria’s northern province of Aleppo.

Fighters with the Manbij Military Council, which is allied with the anti-IS Syrian Democratic Forces, said they are now in control of the majority of the city and their operation to liberate the town would be completed soon.

According to local fighters, nearly 80 percent of the city has been cleared of IS militants.

“There are only small pockets of the city that are still controlled by Daesh [IS],” said Nihad Kani, a fighter with the Manbij Military Council. “We are currently confronting them street to street. But we should defeat them soon.”

Last week, anti-IS forces gave the terror group a 48-hour deadline to surrender their weapons and leave the city, but military leaders said IS militants didn’t leave.

“We offered them the deal to leave the city, because we wanted to save the remaining civilians and avoid bringing more destruction to Manbij,” Adnan Abu Amjad, a commander with the Manbij Military Council, told VOA. “They [IS militants] have not left. So that was the last chance we gave to the terrorist group."

This June 8, 2016 video grab shows smoke rising from the city of Manbij, Syria.

The campaign to liberate Manbij began nearly eight weeks ago, when the anti-IS forces advanced toward the city from several fronts with the help of U.S.-led coalition airstrikes.

So far, the coalition warplanes have conducted more than 500 strikes in support of their local anti-IS fighters.

These military advances come as rights groups in Syria claim that coalition airstrikes have killed dozens of civilians while targeting IS positions inside Manbij.

Civilian deaths

At least 15 civilians were killed as a result of coalition airstrikes near Manbij last week, the Britain-based Syrian Observatory for Human Rights reported.

In response to those claims, the U.S. military is conducting a “credibility assessment” to look into whether there have been any civilian casualties in these attacks, said Colonel Chris Garver, the spokesperson for the U.S.-led coalition.

But local forces said that IS has been using civilians as human shields to deter the coalition from targeting their positions in Manbij and to protract the fight inside the town.

“Daesh [IS] knows that their defeat is imminent now,” said Shervan Derwish, the spokesperson for the Manbij Military Council. “They also want to release some civilians in return for allowing their wounded fighters a safe exist. They are very desperate.”

He told VOA that their forces have rescued hundreds of families who were held by IS in the city.

Manbij had been one of the major supply lines for IS militants in areas they control in Syria. Activists say pushing back IS from the town would be a strategic victory against the terror group.